Can we manage fisheries with the inherent uncertainty from eDNA?

Environmental (e)DNA, as a general approach in aquatic systems, seeks to connect the presence of species' genetic material in the water and hence to infer the species' physical presence. However, fisheries managers face making decisions with risk and uncertainty when eDNA indicates a fish is present but traditional methods fail to capture the fish. In comparison with traditional methods such as nets, electrofishing and piscicides, eDNA approaches have more sources of underlying error that could give rise to false positives. This has resulted in some managers to question whether eDNA can be used to make management decisions because there is no fish in hand. As a relatively new approach, the methods and techniques have quickly evolved to improve confidence in eDNA. By evaluating an eDNA based research programmes through the pattern of the eDNA signal, assay design, experimental design, quality assurance and quality control checks, data analyses and concurrent search for fish using traditional gears, the evidence for fish presence can be evaluated to build confidence in the eDNA approach. The benefits for fisheries management from adopting an eDNA approach are numerous but include cost effectiveness, broader geographic coverage of habitat occupancy, early detection of invasive species, non-lethal stock assessments, exploration of previously inaccessible aquatic environments and discovery of new species hidden beneath the water's surface. At a time when global freshwater and marine fisheries are facing growing threats from over-harvest, pollution and climate change, we anticipate that growing confidence in eDNA will overcome the inherent uncertainty of not having a fish in hand and will empower the informed management actions necessary to protect and restore our fisheries.